Estes Black Star Voyager Build, Part 23, Pre-Painting, Pre-Assembly

There is an open area where the balsa pieces join on the lower fin unit. I decided to fill it.

Some CWF was dropped in using a toothpick and allowed to dry. It took another drop of CWF to fill as the first application shrunk as it dried.

This was sanded with 400 grit on a block.

Thinking ahead - 

TIP: There are visible inside areas that would be impossible to shoot with a spray can once assembled. I could use a brushed enamel paint, but I didn't want to seal the glue areas.

I ended up using an alcohol based "brush" marker. It's a flexible soft marker that allows you to get into tight areas. I couldn't blacken the tightest inside corners, but these areas won't be seen.

More areas that would be hard to reach with a spray can - 

There are tight inside corners at the root edges of the vanes. You might use too much paint tying to cover the surrounding white surfaces.

I went ahead and sprayed some black concentrating on the inside corners. This showed me more glue boogers that required sanding. The pictures show after that sanding.